1. Field of the Invention
The present invention pertains to a phototherapy device and method, and more particularly to a handpiece and method for advancing an optical fiber.
2. Description of the Related Art
Devices and methods for performing various types of laser surgery using optical fibers have become widespread. One relatively new application is myocardial revascularization which is used as an alternative to coronary artery bypass surgery. Trans-myocardial revascularization is a method for treating ischemic heart disease in which the heart muscle or myocardium does not receive an adequate blood supply. Trans-myocardial revascularization helps supplement the blood supply delivered to the heart by providing the heart muscle with direct access to blood within the ventricle chamber.
Lasers have been proposed in trans-myocardial laser revascularization to produce channels in the ventricle wall. The channels provide blood flow to the ischemic heart muscle. Optical fibers are useful for directing laser energy to the desired regions of the heart muscle. However, in order for lasers to be effective in trans-myocardial revascularization, the energy from the laser must be concentrated on a narrow region of the heart tissue. As tissue is ablated, if the optical fiber is held in a fixed position, the surface being cut moves away from the area of greatest laser energy concentration. Consequently, optical fibers are advanced in the cutting direction as the tissue is ablated in order to concentrate energy on the heart tissue. In other words, one may think of the optical fiber as ablating a channel through the heart tissue. If the laser energy is not concentrated on a sufficiently narrow region of the heart tissue, the laser begins to heat up regions of the heart tissue without ablating narrow regions of tissue. This can lead to blood coagulation and damage to the heart tissue.
Devices are known in the art for advancing optical fibers using electric motors. However, such devices are complicated and expensive.
Mechanical devices are also known in which optical fibers are advanced manually by the operator through a rack-and-pinion type of mechanism. However, such devices have the disadvantage that it is difficult to control the speed of the forward advancement since the speed depends on the operator moving a lever or some similar mechanical device.